Threatened red
A California red-legged frog sits atop a patch of sticks and mud. The frog has been on the threatened species list since 1996. Courtesy photo by Spencer Williams
A crew lines the Forest Service pond bed with fish-safe PVC liner. Multiple groups provided supplies and assistance on the project. Courtesy photo
The bottom of the ponds made by the Forest service include at least eight inches of topsoil and discarded tree limbs and logs to provide ample hiding places. Courtesy photo
After construction is complete, the pond is ready for western pond turtles, California red-legged frogs and other wildlife to make a new home. Courtesy photo
A familiar frog has found a favorable foothold in foothill freshwater thanks to efforts by the U.S. Forest Service in the Georgetown Ranger District of the Eldorado National Forest.
The California red-legged frog, or Rana draytonii to its scientist friends, has had a rough time in recent decades with development, over-harvesting, climate change, invasive species and pesticides contributing to the species being added to the U.S. Fish and Wildlife threatened species list in 1996.
Between 2014 and 2016, crews in the northern zone of the Eldorado National Forest began construction of nine areas that would provide potential breeding grounds for the frogs and western pond turtles in the area around Georgetown. Of those initial nine areas, six are still around (three, built in-stream, were blown out in 2017 during the heavy winter), with three serving as a consistent breeding habitat for the red-legged frogs, according to Forest Service aquatic biologist Maura Santora. The ponds have also seen frequent visits from bats, deer and other local wildlife.
The ponds were constructed by digging out wetland depressions about 40 feet across and up to 3 feet deep and then lining the holes with fish-safe PVC liners. The liners were covered on either side with geotextile pads to hold water from snowmelt and rain, and then 8 inches of soil was poured in to allow for plant growth. Supplies and assistance were provided by Partners in Amphibian and Reptile Conservation, American River Conservancy, Save the Frogs and the California Conservation Corps.
“Expanding the available habitat for the population is important and we identified some already disturbed sites, like abandoned logging land, that would make for prime habitat to put them that was already proximate to where we knew they were,” Santora explained. “We were effectively just hoping that if we built it, they would come.”
The ponds now each see one to three red-legged frog egg masses a year. Each egg mass can contain 100-600 eggs, though very few of those eggs will make it through their full life cycle. The frogs, which at their biggest reach about 5 inches long, can live for up to 10 years.
“Maybe 4% or 5% make it to adult stage and only (1%) or so make it the full cycle to reproduction,” Santora said. “But that’s their survival strategy. That’s why they lay so many eggs.”
The Center for Biological Diversity claims the frog has lost close to 90% of its original habitat, which is almost exclusively found in California with rare sightings in Baja California. The Forest Service’s own estimates are more conservative, listing the habitat loss closer to 57%. The frog is found in the coastal region north of Santa Rosa down to Santa Barbara and in the foothills near Redding to just northeast of Fresno, in a range of elevations from sea level to around 5,000 feet.
The frogs were once so commonplace it was a staple cuisine, though they are typically only on the menu for birds, raccoons, snakes and the invasive American bullfrog these days. Their culinary popularity can scarcely hold a candle to their literary fame, however, as experts believe that the celebrated jumping frog of Calaveras County written about by Mark Twain was none other than a red-legged frog. In 2014 the red-legged frog was designated as California’s official state amphibian.
The frogs’ natural elusiveness can make it hard for biologists to gain a clear idea of their population size, particularly in the foothills.
“These are very cryptic little animals,” Santora explained. “They come out at night, they can disperse and forage upland up to 300 feet from water sources and they are really good at hiding under plants and undergrowth in addition to their natural camouflage.”
Though some frogs will stick to the breeding pond it lives in year-round, frogs can disperse as far as 2 miles away from where they were spawned, providing much-needed genetic flow in the region.
Though the population size is uncertain, it’s estimated there are relatively few of the frogs in the Georgetown area. The ponds are providing interesting new data, however, as much of the information on the red-legged frog focuses on how they survive in the more coastal habitat range. Insights on dispersal patterns in the uplands and breeding patterns can help forest managers make decisions that will aid in protecting the threatened species.
The frog populations along the foothills, including the Georgetown and Yosemite groups, are relatively isolated from each other. Yosemite is attempting to lead the charge in upping genetic diversity in breeding pools by translocation of batches of frogs to and from other areas, but the Eldorado National Forest is not at that stage yet.
While the Eldorado National Forest works to identify new potential sites for ponds, Tahoe is in the process of rebuilding its own. Multiple similar pond projects were made in Tahoe National Forest, but were around for only a few years before they were swept away by wildfire.
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